The present invention is directed to a process of producing or cutting openings in a cement bonded construction material including steel reinforcing members, such as concrete or the like, by utilizing drill or chisel bits in a hand-held drilling device.
For forming openings, such as bores, grooves or the like, at the present time, in addition to so-called wall milling, principally drilling or chipping hammers are used. The operation of such devices is based mostly on an electropneumatic system and when compared to impact drilling devices, they show a considerably higher material removal performance.
In the formation of such openings there has been a problem when the bit in the drilling device contacts a steel reinforcing member or rod which, for the most part, is not detectable from the exterior of a structure. The drill bit is very quickly damaged when it contacts a steel reinforcing member due to the impact energy and the bit can be rendered unusable in a short time period.
Detectors are known for locating reinforcing members in construction materials. Such devices, however, are very inaccurate and in practice are usable only for locating reinforcing members positioned directly below the surface. Moreover, such devices are very delicate and from a practical point of view are unsuitable for the rough handling experienced on a construction site.
Furthermore, there are expensive procedures for carrying out the locating operation, such as X-ray technology, ultra-sonic processes or the like, however, for both practical and economic reasons they are not used.